SB 139 
.B7 
Copy 1 



IB 139 



opy 1 



NITED STATES DEPARTMENT OF AGRICULTURE 



DEPARTMENT BULLETIN NO. 1379 





Washington, D. C 



January, 1926 



ELECTROCULTURE 

By Lyman J. Briggs, 1 A. B. Campbell, R. H. Heald, and L. H. Flint, Office 
of Biophysical Investigations, Bureau of Plant Industry 



CONTENTS 



Normal electrical state of the atmosphere 1 

Electrical field employed in electrocultural 

experiments 2 

Electrocultural experiments with miscel- 
laneous crops... 3 

Electrocultural field experiments with grains. 4 
Electrocultural experiments in the plant 
house 13 



Summary of experiments at Arlington Ex- 
periment Farm 15 

Review of other investigations in electrocul- 

ture 17 

Experiments with soil currents 17 

Experiments with modified potential 

gradients. 21 

Literature cited 32 



The term "electroculture" as used in this bulletin refers to practices 
designed to increase the growth and yield of crops through electrical 
treatment, such as the maintenance of an electric charge on a net- 
work over the plants or an electric current through the soil in 
which the plants are growing. 

During the past 75 years many experiments in electroculture have 
been carried out with varying degrees of refinement. Some of these 
experiments indicate that the yield of crops can be materially in- 
creased by electrical treatment. Others, conducted along similar 
lines, fail to show any marked response to the treatment. In this 
latter class are included the experiments conducted by the Office of 
Biophysical Investigations of the Bureau of Plant Industry, which 
are reported in the following pages. This report is followed by a 
brief account of other investigations in this field. Investigations 
relating to the cultivation of plants under electric lights are not in- 
cluded in the review of the literature of electroculture, the response 
of the plants under such conditions being due primarily to the heat 
and light into which the electrical energy has been transformed. 

NORMAL ELECTRICAL STATE OF THE ATMOSPHERE 

Since the effect of using a charged network over growing plants is 
to change the electrical state of the atmosphere surrounding the plants 
it seems desirable to discuss briefly the normal electrical conditions in 
the atmosphere and the changes produced by the charged network. 
An examination of the electrical conditions in the atmosphere over 
an open field on a clear day shows that there is a force tending to 
move a positively charged body downward; in other words, the 
electrical field of force is identical with that which would exist if the 
earth were charged negatively. 

1 Physicist, Bureau of Standards, since 1920. 
62149°— 26f 1 



"irraob 



2 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE 

On fine days, the potential gradient in the atmosphere is almost 
invariably positive in sign (that is, a positive charge tends to move 
downward) , and the magnitude of the vertical gradient is of the order 
of 100 volts per meter, though it is continually varying. When thun- 
derstorms are in the neighborhood, the potential gradient may be 
either positive or negative and changes sign frequently. The magni- 
tude of the potential gradient also undergoes wide fluctuations, 
during stormy weather frequently attaining values of 10,000 volts 
per meter, 100 times the normal gradient. 

A further examination of the lower atmosphere shows that charged 
particles or ions are always present. Both positive and negative 
ions are found, the positive ions generally being somewhat more* 
numerous. They consist of groups of molecules loosely bound 
together and canying a charge. Frequently these small ions attach 
themselves to dust particles, thus becoming large ions, which move 
much less rapidly than the small ions. 

When the potential gradient is positive, the negative ions move 
upward and the positive ions downward to the ground, thus con- 
stituting an electric current flowing from air to earth. This current 
is due almost entirely to the small or free ions, the mobility of the 
large ions being so low that their influence on the conductivity of the 
air can be disregarded. The magnitude of the current from the air 
to a unit area on the earth's surface is extremely small, being only 
2X10" -12 amperes per square meter or 5X10 -8 amperes per acre. 
The strength of the current is proportional to the potential gradient, 
to the number of ions per unit volume, and to their mobility. The 
average number of free ions is of the order of 1,000 per cubic centi- 
meter, the positive ions constituting somewhat more than one-half 
the total number. Their mobility is such that they migrate with a 
velocity of about 1 centimeter per second when subjected to a poten- 
tial gradient of 100 volts per meter. 

Although the air-earth current per unit area is extremely small, 
it is sufficient when applied to the whole of the earth's surface to 
reduce the negative charge of the earth to one-half its initial value in 
about 10 minutes. The explanation of the maintenance of the 
negative charge of the earth under such extraordinary conditions is 
one of the outstanding problems in atmospheric electricity {12, J+l)? 

ELECTRICAL FIELD EMPLOYED IN ELECTROCULTURAL EXPERI- 
MENTS 

In most of the field experiments conducted at the Arlington 
Experiment Farm, the standard height of the network was 5 meters, 
and the potential of the network was approximately 50,000 volts. 
The average potential gradient under the network was therefore of 
the order of 10,000 volts per meter, or about 100 times the normal 
gradient in fine weather. This would produce an air-earth current 
about 100 times the normal current as long as the ion content of the 
air remained normal. However, a marked ionization occurred at the 
network, so that the number of positive ions per unit volume under 
the network was much higher than normal. This was shown by 
means of measurements made when the network was charged and a 
gentle breeze blowing. On the windward side of the network the 
conditions were normal, but on the leeward side a decided increase 



^ The serial numbers (italic) in pare 'thes^t$f^^"^ e <g^ej ! ited>" at the end of this bulletin. 

. RtQEtVfcD 



FEfi'26 1926 






ELECTROCULTTJRE 



was observed in the ion content of the air which drifted from under 
the network. This effect could be traced to a distance of several 
hundred feet from the network. 

The principal change in the environment of plants grown under a 
charged network appears then to consist in a marked increase in the 
strength of the air-earth current which flows through the plants to 
the ground. 

If the drifting charge from the experimental plat should pass over 
the control plat, it would increase the air-earth current to the control 
plat to some extent, owing to the increase in the number of ions per 
unit volume. But even under such conditions the current flowing 
into the control plat would necessarily be small in comparison with 
that flowing into the experimental plat, since both the ion content 
and the potential gradient are much higher under the network and 
the current is proportional to the product of these factors. 

ELECTROCULTURAL EXPERIMENTS WITH MISCELLANEOUS CROPS 

Experiments in 1907. — Electrocultural experiments were first under- 
taken by the department 3 in 1907, using vegetables for the most 
part as test crops. The test plat, which was 138 by 106 feet, was 
divided into three sections 44 by 106 feet, the center section being used 
as the experimental area and the two outside sections as controls. 
The crops were planted in continuous rows across the three sections, 
so that the center third of each row was under treatment. 

A Wagner mica-plate electrostatic machine was used as a high 
potential source. It was inclosed in a tight case, permitting the use 
of drying agents to keep the machine in the best condition for opera- 
tion. The positive pole was connected to an open wire network 
strung on glass insulators, and the negative pole was grounded. The 
network covered the experimental plat and was placed high enough 
to permit the use of a horse cultivator. The applied potential varied 
somewhat with weather conditions, but usually exceeded 50,000 
volts. The network was charged throughout the night, from late 
afternoon until early morning. The plants were subjected to the 
electrical treatment 656 hours in all, extending from June 20 to 
September 16. The yields are shown in Table 1. 

Table 1. — Yields following electrocultural treatment of miscellaneous crops under 
test at Arlington Experiment Farm in 1907 





Yields per plat (pounds) 


Ratio of 


Crop 


Experi- 
mental 
plat 


Control 


Average 

of 
controls 


treated 

to 
average 




Plat A 


PlatC 


of 
controls 




128.25 
20.60 
30.9 
44.0 
55.0 
24.0 
15.0 

106. 05 
20.0 
8.5 


119. 75 
19.14 
40. 14 
52.0 
45*. 
25.0 
18.0 

106.0 
25.0 
10.0 


138. 75 
24.25 
43.0 
39.0 
64.0 
25.0 
17.0 
80.0 
23.0 
11.5 


129. 25 
21.70 
41.57 
45.5 
54.5 
25.0 
17.5 
93.0 
24.0 
10.75 


0.996 




.95 


Cowpea vines. 


.742 
.968 




1.01 




.96 




.856 




1.14 




.835 




.790 







1 These experiments were conducted on the Arlington Experiment Farm by the Office of Biophysical 
Investigations and the Office of Crop Physiology and Breeding Investigations, the field work being handled 
largely by E. W. Hudson and W. r SeifriZ. \ ■',' ' .' 



'\C: 



4 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE 

The lack of uniformity in the yields of the control plats A and C in 
the 1907 experiments (Table 1) is such that no great dependence can 
be placed in these results. It is significant, however, that in only one 
of the 10 trials recorded did the treated plat show any evidence of a 
substantial increase in yield when compared with the mean of the 
control plats. 

Experiments in 1908. — In the 1908 trials the wires were run di- 
rectly over the treated rows and kept at a height of 6 to 18 inches 
above the plants by means of adjustable brackets on which the 
insulators were mounted. The control rows ran parallel to the 
treated ones at a distance of 6 }/% feet and were separated from them 
by intermediate guard rows. 

In one part of the plat the wires over the plants were charged 
positively to about 50,000 volts from 4 p. m. to 7 a. m. each day, 955 
hours in all. In the other part of the plat the wires were charged 
and discharged rapidly by connecting them to one terminal of the 
secondary of an induction coil, the other terminal being grounded. 
In this case the potential ro^e to about 20,000 volts and then dis- 
charged suddenly through a small spark gap between the wires and 
the ground. 

The treatment first described is similar to that employed by Lem- 
strom and believed by him to result in increased yields. In these 
experiments, however, neither treatment gave any evidence of in- 
creased growth. The detailed yields consequently are not of special 
interest. 

ELECTROCULTURAL FIELD EXPERIMENTS WITH GRAINS 

In selecting a location for the electrocultural field experiments near 
Washington, three conditions were sought: (1) A uniform soil, (2) 
available electric power, and (3) accessibility from the laboratory in 
Washington, since the equipment had to be visited daily during the 
experimental season. Soil uniformity is particularly difficult to find 
in the environs of Washington, and the Arlington Experiment Farm 
forms no exception in this respect. It seemed to be the best avail- 
able location, however, and portions of sections A, B, and E were 
made available for the experiments, which were carried on from 1911 
to 1918. Sections A and B proved very disappointing with regard 
to their uniformity, and the most reliable results were obtained in 
section E. These experiments will be first described. 

The Lodge-Newman apparatus used in the experiments from 1912 
to 1915, inclusive, was designed in England primarily for electro- 
cultural work and consists essentially of a 110-volt induction coil, 
operated by a mercury interrupter, and a rectifier. Five Lodge 
valves 4 designed to rectify the high-tension alternating current were 
placed in series with the network, thus allowing only the positive 
impulses from the secondary of the coil to reach the network (33). 
The negative pole was grounded. Two balls 25 millimeters in diam- 
eter, one of which was grounded and the other connected to the net- 
work, were used to determine the potential, assuming a breakdown 
gradient of 3,000 volts per millimeter. 

Systematic measurements of the current from the network were 
not made, but the current could be determined approximately from 
the potential of the network and the known power characteristics of 

* For a description of the valves, see Lodge, O. (.84). 



ELECTROCULTURE 5 

the machine used. The current from the network over the experi- 
mental plat in section E was of the order of 0.1 to 1 milliampere per 
acre, depending on the voltage and network used. This is of the 
order of 10,000 to 100,000 times the intensity of the normal air-earth 
current. 

EXPERIMENTS IN SECTION E 

It has been shown by j0rgensen and Priestley {26) that the ioniza- 
tion from the highly charged network is by no means limited to the 
area beneath the network, but may be carried by the wind to a con- 
siderable distance, depending on the weather conditions. It was 
consequently deemed advisable to separate the treated and control 
plats so far as practicable. Accordingly, two plats of half an acre 
each (132 by 165 feet) were selected in section E which were sepa- 
rated by a distance of 350 feet, one plat being directly north of the 
other. 



ygrfftiitt^ Hi in 1 : 

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Fig. 1. — General view of the experimental field at Arlington Experiment Farm, showing the 
system of double insulators used in suspending the wire network from poles and the power lines 
leading to the motor in the apparatus house (foreground) . Poles supporting the grounded net- 
work along the side of the control plat may be seen in the distance. (Photographed May 8, 1918.) 

The rye which was growing on the plats of section E when they 
were selected in 1913 was cut and weighed. The results show that 
the productiveness of the two plats was about the same, being as 
follows: Yield of south plat, 2,438 pounds; of north plat, 2,499 pounds; 
ratio of south plat to north plat 0.98. 

Experiments in 1914- — A network 16 feet high was erected over the 
south plat, having cross wires at intervals of 15 feet. (Fig. 1.) 
Winter wheat was sown on both plats the following October, and the 
treatment was given by means of the Lodge-Newman apparatus, 
which furnished a positive charge to the network at a potential 
ranging from 30,000 to 60,000 volts. The treatment was given in 
the fall and spring from 3 to 7 p. m., a total of 336 hours. The grain 
was harvested in June, 1914, giving yields which were substantially 
the same for both plats, as shown in Table 2. 



BULLETIN 1379, U. S. DEPARTMENT OP AGRICULTURE 



Table 2. — Yields of winter wheat on -plats following electrocultural treatment (posi- 
tive charge), section E, Arlington Experiment Farm, in 1914 



Plat 



Treated. 
Control _ 



Yields (pounds) 



Shock 



2,332 
2,281 



Grain 



644.8 
656.5 



Ratio of treated 
to control 



Shock 



1.02 



Grain 



0.97 



Experiments in 1915. — Wheat was again sown in the autumn of 
1914. The fall treatment was omitted, owing to bad weather. In 
1915 the network was charged positively by the Lodge- Newman 
apparatus twice a day from 4 to 7 a. m. and from 5 to 8.30 p. m., a 
total of 345 hours. The distance between the cross wires of the net- 
work this year was 6 feet. The plats were divided at harvest into 
east and west halves. The yields are shown in Table 3. 

In both plats two bad spo^s developed on the western halves, in 
which the grain was much poorer than the average. 

Table 3. — Yields of winter wheat on plats following electrocultural treatment (posi- 
tive charge), section E, Arlington Experiment Farm, in 1915 



Plat 



Eastern half: 

Treated 

Control 

Western half: 

Treated 

Control 

Total: 

Treated 
Control- 



Yields (pounds) 



Shock Grain 



832 
822 

716 
540 

1,548 
1,362 



321.5 
350 



303 
254.5 



624.5 
604.5 



Ratio of treated 
to control 



Shock 



1.01 
1.32 
1.14 



Grain 



0.92 
1.19 
1.03 



Experiments in 1916. — In the fall of 1915 winter wheat was again 
sown, as it was desired to get a test with the network charged 
negatively, about 45,000 volts, instead of positively as heretofore. 
A powerful static machine was used to supply the current, and it 
was run from 4 p. m. to 8 a. m. daily (totaling 800 hours) during 
the spring, the fall treatment being omitted. 

The plats were divided into eastern and western halves at the 
time of harvest and again showed considerable variation. The 
yields are given in Table 4. 

Table 4. — Yields of winter wheat on plats following electrocultural (negative) 
treatment, section E, Arlington Experiment Farm, in 1916 



Plat 


Yields (pounds) 


Ratio of treated 
to control 




Shock 


Grain 


Shock 


Grain 


Eastern half: 


1,324 

1,352 

1,204 
1,092 

2,528 
2,444 


347.5 
411.0 

324.5 
343.0 

672.0 
754.0 


} 0.98 
| 1. 10 
} 1.03 


0.85 




Western half: 




Control 

Total: 


.89 
















ELECTROCULTURE 



Experiments in 1917. — Wheat was again sown in section E in 
October, 1916, and allowed to mature the following summer without 
treatment, as an additional check on the soil conditions. At time of 
harvest in 1917 the plats were again cut into eastern and western 
halves, the south plat being the one which had received the elec- 
trical treatment in previous years. The yields are shown in Table 5. 

Comparison with the rye yields of 1913 shows that the south 
(treated) plat apparently gained slightly in its relative productivity 
during the five years, but the change is well within the errors of field 
trials. 

Table 5. — Yields of winter wheat on plats without electrocultural treatments, 
section E, Arlington Experiment Farm, in 1917 



Plat 



Yields (pounds) 



Shock- 



Eastern half: 
South plat. 
North plat- 
Western half: 
South plat_ 
North plat . 
Total: 

South plat. 



1, 028. 
1, 025. 

1, 502. 5 
1, 439. 5 

3, 190. 5 
North plat 3,004.5 



Grain 



580. 5 
031.0 



557.0 
567.5 



1,137.5 
1,198.5 



Ratio of south to 
north plats 



Shock 



1.00 
1.08 
1.04 



Grain 



0.92 

.98 
.95 



Experiments in 191S. — In the fall of 1917 winter wheat (Ourrell) 
was sown on the plats in section E, and in the spring a i^-inch mesh 
galvanized-iron screen 132 feet long by 15 feet high was erected 20 
feet south of the check plat. It was thought that the grounded 
screen might protect the north plat from the drifting charge, but 
later measurements show that it is of doubtful value. 

The static machine was again used, with the positive pole con- 
nected to the network. The number of cross wires was increased 
to one every 3 feet. This increased the current and reduced the 
potential of the network to about 30,000 volts. 

Although the winter was exceptionally cold the stand in the spring 
was excellent. Treatment was started April 15 and continued for 
46 days from 4 p. m. to 8 a. m. each day, a total of 736 hours. 

At harvest the eastern and western halves of each plat were kept 
separate and weighed. The yields are shown in Table 6. 

Table 6. — Yields of winter wheat on plats following electrocultural treatment (posi- 
tive charge), section E, Arlington Experiment Farm, in 1918 



Plat 


Yields (pounds) 


Ratio of treated 
to control 




Shock 


Grain 


Shock 


Grain 


Eastern half: 

Treated . 

Control 


1,531 

1, 332 

1,289 
1,307 

2,820 

2, 639 • 


569 

518 

481 
507 

1,050 

1,025 


\ 1. 10 
} .99 
} 1.07 


1.10 


Western half: 

Treated 




Control .. _- 


. 95 


Total: 






1. 02 







8 



BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE 



A general view of the experimental field as it appeared on May 8, 
1918, is shown in Figure 1. 

After the 1918 crop was harvested, measurements of the charge 
carried by the wind were undertaken. A flame collector was used, 
which was connected to the gold leaf of an electroscope, the case 
being grounded. A full-scale deflection of 25 divisions represented 
a potential of about 1,000 volts. In all the measurements the 
collector was held at a height of 1 meter above the ground. 

A light south wind was blowing the day the measurements were 
made. With no charge on the network, a very slight deflection of 
the gold leaf could be noticed. With the network charged, however, 
the full-scale deflection occurred very rapidly at any point under and 
within 20 feet outside the network on all sides, even to the south, 
the direction from which the wind was coming. At 50 feet south, 
only about 1 division deflection was obtained. North from the net- 
work the deflection to full scale was slower and more irregular the 
greater the distance from the network, and when only 2 feet south of 
the screen along the south side of the north plat the maximum deflec- 
tion obtainable was about 20 divisions. Just north of the grounded 
screen the maximum deflection obtained was about 9 divisions. As 
the collector was moved farther north from the screen and into the 
control plat, the deflection again increased, until at the center of the 
control plat it was off the scale again. The grounded screen along 
the south side of the control plat thus afforded little protection from 
the drifting charge. At a point 1,000 feet from the network, the 
last point observed, a full-scale deflection was obtained. At all 
points beyond 100 feet from the network over the south plat the 
deflection was very irregular and unsteady. 

The Weather Bureau records show that during the 46 days of 
treatment in 1918 the wind was due south only 3 days. Owing to 
the distance of 350 feet between the treated and control plats, the 
wind would have to be nearly due south to carry any appreciable 
charge over the control plat. 

SUMMARY OF EXPERIMENTS IN SECTION E 

The relative yields of the south (treated) and north plats in section 
E are summarized in Table 7. 

Table 7. — Summary of yields of rye and winter wheat on the south (treated) and 
north (untreated) plats, section E, Arlington Experiment Farm, in six stated 
years 



Year 


Crop 


Treatment 

of south 

plat 


Ratio of yields of 
south to north plats 


Year 


Crop 


Treatment 

of south 

plat 


Ratio of yields of 
south to north plats 




Total 


Grain 


Total 


Grain 


1913 


Rye 

Wheat... 
...do 




0.98 




1916 
1917 
1918 


Wheat... 

...do 

...do 


Negative... 

None 

Positive 


1.03 
1.04 
1.07 


0.89 


1914 
1915 


Positive 

...do 


1.02 
1.14 


0.97 
1.03 


.95 
1.02 



It is evident from the summary that the electrical treatment did not 
produce any sensible increase in yield. An examination of the detailed 
results for 1915 shows that the somewhat higher ratios obtained dur- 
ing this unfavorable year are due to a marked decrease in yield in 



ELECTROCULTUEE 



9 



half of the control plat. Aside from this, there appears to be a gradual 
increase in the total yield of the south plat relative to the north one, 
irrespective of whether a positive charge, a negative charge, or no 
charge at all was used. It is of interest to note that the grain ratios 
with a positive charge on the network are all slightly higher than the 
ratio in 1917, when no treatment was given; with the negative charge 
the reverse is true. This seems consistent, for if increasing the posi- 
tive gradient of the electrostatic field tends to stimulate growth, then 
to reverse the sign of the field may perhaps tend to inhibit growth. 
Opposed to this speculation is the fact that the negative field appar- 
ently had no effect on the ratio of the total yields of the two plats. 
In brief, while there is some evidence of a slight increase in grain 
yield when wheat is grown under a network which is positively charged 
to a high potential, the observed effect is so small that it is well within 
the experimental errors of field trials. 



EXPERIMENTS IN SECTION B 



Experiments in 1911. — The first electrocultural field experiments at 
Arlington Experiment Farm were made in 1911 with grains in sec- 
tion B, employing a plat which had been seeded in strips to wheat 
the previous fall. In the spring of 1911 a network of small wire was 
installed over the eastern half of the plat, covering half of each 
variety. The network was 7 feet high with wires at intervals of 3 
feet, connected to the positive pole of a static machine operating at 
a potential of about 40 to 50 kilovolts. The machine was in opera- 
tion six days a week from 3 p. m. to 7 a. m. except during rainy 
weather from early spring to harvest. 

Table 8 shows the relative yields of the treated and control halves. 



Table 8.- 


— Yields of winter wheat on plats following electrocultural treatment (posi- 
tive charge), section B, Arlington Experiment Farm, in 1911 




Variety 


Yields per acre (pounds) 


Ratio of 

grain, 

treated to 




Treated half 


Control half 




Grain 


Straw 


Grain 


Straw 




Q. I. 1942 


820 1,740 
1, 320 1, 920 
1, 240 2. .520 


780 
1,450 
1,300 


1, 3fi0 
2,070 


1.05 


Fultz 


.91 


Q. I. 1974... 


.95 













Experiments in 1912. — In the fall of 1911 one variety of wheat, 
Currell (CurrelVs Prolific), was sown on section B, and the network 
was again erected at the height of 7 feet with cross wires 3 feet apart, 
as before. The treated and control plats each had an area of three- 
fourths of an acre. This year the network was charged with a 
Snook-Roentgen set, which consisted of an inverted rotary converter 
supplying a 160-volt current to a 1-kilowatt 100,000-volt transformer. 
A mechanical rectifier was used on the high-tension side to obtain a 
positive charge on the network, the other terminal of the trans- 
former being grounded. Even with this set it was not possible to 
charge the network much above 50,000 volts. The treatment was 
given daily from 3 to 7 p. m., except Sundays and during bad weather. 

At harvest the weights shown in Table 9 were recorded. 
62149°— 26 2 



10 



BULLETIN 1379', U. S. DEPARTMENT OF AGRICULTURE 



Table 9. — Yields of winter wheat on plats folio wing clectrocultural treatment (posi- 
tive charge), section B, Arlington Experiment Farm, in 1912 





Yields (pounds) 


Ratio of treated to control 


Plat 


Shock 


Orain 


Straw 


Shock 


Grain 


Straw 




3,465 
3,300 


1,154 

1,114 


2.311 
2,186 


| 1.05 


1.04 


1.06 









Experiments in 1913. — In the fall of 1912 the same plat in section B 
was again sown to wheat. The 7-foot network of the previous year 
was replaced by a permanent one 16 feet high, with cross wires 10 
yards apart. The new network was erected over the northern half 
of the plat instead of the eastern half as in preceding years. The 
network was charged positively with the Lodge-Newman apparatus, 
and the treatment was given daily from 4 p. m. to 8 a. m. 

The treated and control portions each had an area of three-fourths 
of an acre. At harvest the. weights shown in Table 10 were recorded. 

After the wheat was cut, cowpeas were sown on the B plat on 
July 29, 1913. 

The static machine was connected to the network (16 feet high), 
giving about 40 to 50 kilovolts. The machine (positive charge) was 
run four hours a day from 3 to 7 p. m. for 32 clays. On account of 
the lateness of the season, the cowpeas were cut for hay. After being 
stacked and cured, the crop was weighed in the field by means of a 
tripod and spring balance, showing the following yields: Treated por- 
tion, 1,807 pounds; control portion, 1,847 pounds; ratio of treated to 
control, 0.98. 

Table 10. — Yields of winter wheat on plats following clectrocultural treatment (posi- 
tive charge), section B, Arlington Experiment Farm, in 1913 



Plat 


Yields (pounds) 


Ratio of treated to 
control 




Shock 


Grain 


Shock 


Orain 




3, 254 

3,139 


808 

782 


} 1.04 






1.03 







Experiments in 1914- — Corn was planted in the B plat on May 24, 
1914, and the network (16 feet high) was connected directly to one 
wire of a 6,600-volt 3-phase 25-cycle alternating-current power line 
running past the farm. The voltage was on continuously day and 
night for 110 days, when the corn was cut and the total weights 
recorded in the field. It was then shocked and given time to dry. 
Husking was done in the field on October 9 ; 1914, and the grain and 
fodder brought to a platform balance in the barn and weighed. The 
superintendent of the farm expressed the opinion that the treated 
plat had had some advantage over the check plat as regards soil- 
moisture conditions. The yields shown in Table 11 were recorded. 



ELECTBOCULTUEE 



11 



Table 11.- 



-Yields of corn on plats following electrocultural treatment (alternating 
charge), section B, Arlington Experiment Farm, in 1914 





Yields (pounds) 


Ratio of treated to control 


Plat 


Green 
shocks 


Dry 

shocks 


Grain 
(on cob) 


Green 
shocks 


Dry 

shocks 


Grain 
(on cob) 


Treated 


16,031.5 
13, 775. 5 


4,060 
3,952 


2,892 
2,260 


} 1.16 


1.03 




Control.-- 


1.28 







Experiments in 1915. — The corn was followed by rye which was 
sown in section B on October 22, 1914. The 6,600-volt treatment 
alternating charge was started November 5 and maintained continu- 
ously till June 24, 1915. This year at time of harvest each plat 
(treated and control) was divided into eastern and western halves, 
and each section was weighed separately to show any inequalities in 
soil conditions. 

The yields recorded at harvest showed a lack of uniformity in the 
plats, but gave no evidence of a sensible increase in yield due to the 
electrical treatment. The results are shown in- Table 12. 

Table 12. — Yields of rye on plats following electrocultural treatment [alternating 
charge), section B, Arlington Experiment Farm, in 1915 



Plat 


Yields (pounds) 


Ratio of treated to 
control 




Shock 


Grain 


Shock 


Grain 


Eastern half: 

Treated 


1,532 
1,350 

1,304 
1,408 

2,836 
2,758 


565 
525 

481 
515 

1,046 
1,040 


} 1.13 
} .93 
} 1.03 




Control.- -- 


L08 


Western half: 

Treated 




Control.. 


.93 


Total: 

Treated. 




Control 


L01 







Experiments in 1916. — In order to measure the relative yielding 
power of the two plats (treated and control) under normal condi- 
tions wheat was again sown in the fall of 1915 and allowed to mature 
the following summer without electrical treatment of either plat. 
Table 13 shows the figures recorded at harvest, the north plat being 
the treated plat of the three preceding years. 

Table 13. — Yields of winter wheat on plats without electrocultural treatments, 
section B, Arlington Experiment Farm, in 1916 



Plat 



Yields (pounds) 



Shock Grain 



Ratio of north to 
south plats 



Shock 



Grain 



Eastern half: 

North plat 

South plat 

Western half: 

North plat 

South plat 

Total: 

North plat 
South plat 



1,568 
1,660 



1,448 
1,752 



3,016 
3,412 



456.5 
542.0 



403. 5 
407. 



861. 
1, 009. 



0.95 



0.84 
.86 
.85 



12 



BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE 



SUMMARY OF EXPERIMENTS IN SECTION B 

The 1916 results show about 15 per cent difference in the yield of 
the plats when no electrical treatment was used, the control plat 
giving the higher yield. During the preceding three years the yields 
of the two plats were approximately equal. If the 1916 results are 
accepted as indicating the relative productivit} 7- of the two plats 
under normal conditions, the conclusion follows that during the pre- 
ceding three years the electro cultural treatment increased the yield 
15 per cent or more and that an alternating charge on the network 
was equally as effective as a high positive charge. During the time 
the network was connected to the alternating-current power line the 
charge was changing sign 50 times per second, the maximum gradient 
was about 1,500 volts per meter, and there was no appreciable ioniza- 
tion at the network. The conditions were so different from those 
prevailing when the network was charged to a steady high positive 
potential that it seems highly improbable that the effect on the grow- 
ing crop would be the same unless the effect is nil under both condi- 
tions, the 1916 results not being representative. The latter conclu- 
sion seems the more probable, and this is supported by the experi- 
ments in section A which follow. 

EXPERIMENTS IN SECTION A 

A plat in section A of the same dimensions as the one in B was also 
used for electrocultural tests. The north half of this plat was 
equipped with a 16-foot network similar to the B network except that 
it had twice as many cross wires (5 yards apart) . The two networks 
were connected electrically, so that both received the same charge. 

Experiments in 1914- — Soybeans were planted in section A in June, 
1914, and subjected to a 6,600-volt 25-cycle treatment (alternating 
charge) continuously from July 15 to October 19, when the crop was 
harvested. The total weight of the crop from each plat was deter- 
mined just after cutting, again after drying in the field, and finally 
after threshing. The weights recorded are shown in Table 14. 

Table 14.— Yields of soybeans on plats following electrocultural treatments {alter- 
nating charge), section A, Arlington Experiment Farm, in 1914 





Yields (pounds) 


Ratio of treated to control 


Plat 


After 
cutting 


After 
drying 


Beans 
only 


After 
cutting 


After 
drying 


Beans 
only 


Treated * 


4,093 
4,242 


2,776 
2,446 


811.3 
782.5 


| 0. 97 


1.13 


1.04 









Experiments in 1915. — After the plat had been plowed and put in 
good shape, rye was seeded on October 22, 1914, and the 6,600-volt 
treatment (alternating charge) was started November 5 and main- 
tained continuously until harvest. The field was divided into four 
equal parts when the rye was cut, to get some idea of the soil variation 
in the eastern and western halves of the plats. At harvest time the 
crop under the network showed a much better growth than the con- 
trol plat, but this was probably owing to soil conditions rather than 
to the electrical treatment, as indicated by the comparative test the 
following year. The yields obtained are shown in Table 15. 



ELECTROCULTTJRE 



13 



Table 15. — Yields of rye on plats following electrocultural treatments (alternating 
charge), section A, Arlington Experiment Farm, in 1915 



Plat 


Yields (pounds) 


Ratio of treated 
to control 




Shock 


Grain 


Shock 


Grain 


Eastern half: 

Treated 


1,270 
868 

1,392 
890 

2,662 

1,758 


469 
363 

512 
337 

981 
700 


} 1.46 
| 1.56 
} 1.51 




Control 


1.29 


Western half: 

Treated 




Control 


1.52 


Total: 

Treated 




Control 


1.40 







Experiments in 1916. — Rye was again sown in section A in the 
fall of 1915 and allowed to mature without electric treatment. This 
crop was cut in June, 1916, giving the yields shown in Table 16, the 
north plat being the plat treated during the two preceding years. 

Table 16. — Yields of rye on plats without electrocultural treatments, section A, 
Arlington Experiment Farm, in 1916 



Plat 


Yields (pounds) 


Ratio of north 
to south 




Shock 


Grain 


Shock 


Grain 


Eastern half: 

North 


1,802 
1,328 

1,892 
1,230 

3,694 
2,558 


557 
409.5 

590.5 
393.5 

1, 147. 5 
803.0 


} 1.36 
\ 1.54 
} 1.44 




South 


1.36 


Western half: 

North 




South 


1.50 


Total: 

North 




South 


1.43 







SUMMARY OF EXPERIMENTS IN SECTION A 

A comparison of the yields obtained in the field trials in section 
A gives no evidence of an increased yield accompanying the use of 
an alternating charge on the network. 

ELECTROCULTURAL EXPERIMENTS IN THE PLANT HOUSE 

TRANSPIRATION 

The effect of a very high potential gradient on the transpiration 
rate was investigated in plant-house experiments in Washington in 
1913. Large galvanized-iron buckets were filled with moist soil 
and fitted with special covers to prevent evaporation from the soil. 
Six rooted geranium cuttings were planted in each pot through 
holes in the cover, the opening around the stem of the plant being 
sealed with wax. 

The initial weights were taken on February 15, 1913, and the 
plants were allowed to grow until February 20 without treatment, 
to determine the relative transpiration of two sets of six pots each. 
One set was then placed under an insulated frame covered with 
galvanized- wire screen of y% -inch mesh, while the control set was 
protected from the discharge by being placed inside a Faraday 



14 



BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE 



cage of 3^-inch mesh. The frame was connected to the positive 
pole of the static machine, the other pole being grounded. The 
frame was charged four hours a day, from 3 to 7 p. m., from February 
21 to March 24. The plants were again allowed to grow without 
treatment from March 25 to April 7. During each period weigh- 
ings were made to determine the loss due to transpiration, and 
water was added when necessary to maintain approximately the 
initial moisture content of the soil. 

Table 17 shows the rate of transpiration for each pot during the 
three periods and the ratio of the treated to the control set. It 
will be noted that during the period of treatment no sensible change 
occurred in the transpiration ratio. 

Table 17. — Transpiration rate of geranium plants in pots under electrocultural 
treatment in the plant house at Washington, D. C, in 1913 








Transpiration rate per hour (grams) 


Pot designation 


No treatment 


Treatment period 


No treatment 




Feb. 15 
to 17 


Feb. 17 

to 20 


Feb. 20 
to 25 


Feb. 25 

to 
Mar. 1 


Mar. 1 
to 5 


Mar. 5 
to 13 


Mar. 13 
to 24 


Mar. 24 

to 
Apr. 1 


Apr. 1 
to 7 


Treated set: 

No. 175 


3.6 
3.3 
2.9 
2.6 
4.3 
2. 1 


5.1 
4.7 
5.3 
4.7 
8.1 
5.0 


5.1 
5.1 
4.8 
4.4 
6.4 
4.9 


2.9 
3.4 
2.9 
2.9 
3.3 
3.2 


8.3 
8.4 
8.1 

7.7 
9.7 
7.9 


8.0 
8.0 
7.6 
7.4 
7.9 
6.8 


8.8 
9.5 
9.0 
9.4 

7.7 
8.7 


7.7 
8.2 
7.7 
8.9 
6.8 
8.6 


10.5 


No. 176.. 


10.9 


No. 177... 


10.9 


No. 178... 


11.4 


No. 179 


10.4 


No. 180 


11.4 








3.13 


5.15 


5.11 


3.10 


8.35 


7.61 


8.85 


7.98 


10.91 






Control set: 

No. 181 


3.1 
3.3 
3.3 
3.6 

4.3 
3.6 


4.2 
5.7 
4.6 
5.0 
5.7 
5.3 


4.3 
6.0 
5.2 
4.9 
5.9 
5.5 


2.8 
3.7 
3.4 
3.2 
4.0 
3.5 


7.0 
8.6 
8.1 
8.0 
9.0 
8.7 


6.5 
8.0 
7.6 
7.6 
8.2 
8.4 


8.4 
8.6 
8.9 
8.9 
8.1 
8.6 


9.1 
7.3 
8.2 

8.4 
7.1 
7.4 


11.1 


No. 182 


10.7 


No. 188 


10.6 


No. 184 . 


10.9 


No. 185 


10.3 


No. 186... 


10.6 








3.53 


5.08 


5.30 


3.43 


.8.23 


7.71 


8.58 


7.91 


10.70 






Ratio of treated to control . . . 


.89 


1.01 


.97 


.91 


1.01 


.99 


1.03 


1.01 


1.02 



The total transpiration from the treated and control sets of potted 
geranium plants for the three experimental periods is given in 
Table 18. 

Table 18. — Total transpiration oj geranium plants in pots during the three experi- 
mental periods in the plant house at Washington, D. C, in 1913 





Total transpiration (kilo- 
grams) 


Designation 


No treat- 
ment, 

Feb. 15 
to 20 


Treat- 
ment 
period, 
Feb. 21 to 
Mar. 24 


No treat- 
ment, 
Mar. 25 
to Apr. 7 


Treated set 


3.00 

3.08 


33.42 
33.42 


20.01 


Control set . 


19.62 








.98 


1.00 


1.02 







ELECTROCULTURE 15 

WATER REQUIREMENT 

An investigation of the effect of a high potential gradient on the 
water requirement of cowpeas was undertaken in a plant house 
during the winter of 1918. Eighteen large galvanized-iron cans, 
each holding about 125 kilograms, were filled with well-mixed soil 
and fitted w^th special covers to prevent evaporation. The cow- 
peas were planted through holes in the covers, the openings being 
sealed with w&x. The pots were weighed at the beginning and at 
the end of the experiment, and a record was kept of the water added 
to each pot, from which the total quantity of water transpired by 
the plants in each pot could be determined. In brief, the procedure 
was that followed by Briggs and Shantz (10, 11) in their water- 
requirement measurements. 

These pots were divided into three sets of sLx each. Set No. 1 
was placed on an insulated stand, with each pot connected to the 
positive pole of a static machine; set No. 2 was grounded and placed 
under a positively charged iron-wire screen suspended about 2 feet 
above the plants; and set No. 3 was used as a control and was protected 
from the influence of the charged sets by a well-grounded ware screen. 
The potential supplied by the static machine was above 50,000 volts. 

As soon as the treatment started trouble was experienced with 
the set beneath the charged network, soot and dust (large ions) being 
deposited on the leaves and stems of the plants, and in fact all over 
the house. A coating would collect on the leaves over night during 
the course of a 16-hour treatment. The plants were washed several 
times, but they did not thrive, owing in part at least to the great 
reduction in photosynthesis resulting from the coating on the leaves. 
This set was finally discarded. 

The other two sets, however, grew well throughout the experi- 
ment, although they were not so vigorous as plants grown out of 
doors in the summer. The positions of the pots in a given set were 
interchanged weekly, so as to provide average light conditions for 
each pot. 

The plants were cut May 2, after 54 days of treatment for 16 hours 
each day (from 4 p. m. to 8 a. m.), and they were dried at 100° C. 
and weighed. The water requirement of the plants in each pot 
w T as computed by dividing the total w T eight of water transpired 
by the dry weight of the crop. The mean water requirement for 
each set of six pots with its probable error was as follows: For the 
treated set. 449 ±4; for the control set, 429 ±5. A slightly higher 
w r ater requirement is thus showm for the treated set, the observed 
increase being 4 ±1.2 per cent. If some of the water molecules 
escaping through the stomata of the leaves carried a positive charge, 
they w r ould move away from the leaf more rapidly than under normal 
conditions, owing to the strong electric field. This would be equiva- 
lent to a virtual increase in the vapor pressure gradient near the 
leaf and would tend to increase the evaporation rate. Although the 
above suggestion is highly speculative, it would be of interest to 
repeat the experiment, applying the electric charge during the 
daylight hours when the transpiration rate is highest. 

SUMMARY OF EXPERIMENTS AT ARLINGTON EXPERIMENT FARM 

Electrocultural experiments extending over a period of eight years 
have been conducted at the Arlington Experiment Farm, Rosslyn, 
Va., for the purpose of determining whether a highly charged network 



16 



BULLETIN 1379, U. S. DEPARTMENT OP AGRICULTURE 



will increase the yield of crops growing under it. The electrical 
treatment was usually given during the early-morning and late- 
afternoon hours. The general experimental procedure was similar 
to that employed in experiments in England in which the electrical 
treatment is reported to have given increased yields. 

These experiments do not show any well-defined increase in yield 
due to electrical treatment. There is an indication of a slight 
increase in the yield of wheat when grown under a positively charged 
network, but the observed increase is well within the experimental 
error of field trials. 

The results of these field experiments are summarized in Table 19. 
The relative productivity of the plats when not subjected to the 
electrical field was determined in order to provide additional informa- 
tion in interpreting the results, a precaution which has not been 
generally observed by other investigators. A discussion of the 
yields from each section will be found in the text embodying the 
description of the experiments. 

Table 19. — Summary of the results of the electrocultural experiments in sections A, 
B, and E, Arlington Experiment Farm, in stated years 

[The treated and control plats in sections A and B were each three-fourths of an acre in area; those in section 
E half an acre each, separated by an interval of 350 feet. Abbreriations and symbols. — Column 2: C = Cow- 
peas (crop cut for hay); R = Winter rye; S = Soyheans; \V = Winter wheat. Column 3: Numbers refer 
to preceding tables. Column 4: A=25-cycle alternating current; N = No treatment; — = Negative 
direct current; + = Positive direct current. Column 12: * = Yield of plats treated in previous years] 





















Ratio of 










Network treatment 


Yields (pounds) 




treated 
to 




Crop 


O 














control 


Section and date 


Character 
of current 


Descrip- 
tion of 
net- 
work 


Time of 

treatment 

(hours) 


Dry shock 


Grain 


















a 















































•2 

3 


03 


CD 

St 

M 


2 

be 


til 

a 
'3 


a 

'•3 


■a 




a 


•a 
a 


O 


M 

a 


>. 


a 
'3 










O 














c 












H 


u 


> 


w 


CQ 


Ph 


H 


^ 





E-| 


c 


w 


O 


1 


2 


3 


4 


5 


6 


7 


8 


9 


10 


11 


12 


13 


14 


15 


Section A: 






























1914. 


S 

R 

R 


14 
15 
16 


A 
A 

N 


6,600 

6,600 


16 
16 

16 


5 
5 

5 






2,776 
2, 662 


2,446 
1,758 
2,558 


811.3 
981 
•1,147.5 


782.5 

700 

803 


1.13 

1.51 
1.44 


1 04 


1915.. 






1.40 


1916 






2,700 


1 43 


Section B: 








1912 


\V 


9 


+ 


45, 000 
(40,000 


7 
1 


1 


i 16 


3.' 


3,300 


1,154 


1,114 


1.05 


1.04 










1913 


w 


10 


+ 


\ to 

[50, 000 


" 


10 


2 16 


.... 


3,254 


3,139 


808 


782 


1.04 


1.03 






1913 


c 




+ 
A 
A 

N 


45,000 


16 
16 

16 


10 
10 
10 


•4 


128 


1,807 
6,952 
2,836 
3,016 


1,847 
6,212 
2,758 
3,412 






.98 
1.12 
1. 03 

.88 




1914 


Corn 

R 

W 


11 
12 

i:i 


2,892 
1,046 
•861 


2, 260 
1,040 
1,009 


1 88 


1915. 






1 01 


1916 






,85 


Section E: 














1913 


R 


7 


N 












2,438 


2,499 






98 












(30,000 


) 




















1914 


W 


2 


+ 


\ to 

loo, 000 


\u 


5 


M 


336 


2,332 


2,281 


644.8 


656.5 


1.02 


.97 














(30, 000 


1 




















1915 


W 


3 


+ 


\ to 
(60, 000 


" 


2 


a WA 


345 


1,548 


1,362 


624.5 


604.5 


1.14 


1.03 






1916 


W 

w 

W* 


4 
5 
6 


N 
+ 


45,000 


16 


2 


1 16 


800 


2,528 
3, 190. 5 
2,820 


2,444 

3,064.5 

2,639 


672 
1, 137. 5 
•1,050 


7.54 
1, 198. 5 
1,025 


1.03 
1.04 
1.07 


.89 


1917. 


95 


1918 


30,000 


16 


1 


1 16 


736 


1 02 







1 From 4 p. m. to 8 a. m. 

2 From 3 to 7 p. m. 



3 From 4 to 7 a. m. and from 5 to 8.30 p. m. 

4 Plats separated by grounded wire screen. 



ELECTROCTJLTURE 17 

Plant-house experiments were also made on the effect of an electric 
charge on the transpiration rate and the water requirement of plants. 
The effect observed was well within the errors of experiment. 

The use of electrocultural methods in their present state of develop- 
ment as a practical means of increasing the yield of crops in this country 
is not recommended. 

REVIEW OF OTHER INVESTIGATIONS IN ELECTROCULTURE 

Electrocultural experiments may be divided into two main classes: 
(1) Those in which the soil is the medium of conduction and (2) 
those in which the air is the medium of conduction. Experiments of 
the first class cover the use of soil currents resulting (1) from an 
externally applied electromotive force, (2) from the galvanic action 
of the soil moisture on zinc and copper plates buried in the ground, 
and (3) from the use of metallic uprights designed to collect and 
carry atmospheric electricity to the soil. Experiments of the second 
class are those in which the normal air-earth current is increased by 
means of a highly charged network over the plants or decreased by 
inclosing the plants in a grounded cage made of metal screen. 

EXPERIMENTS WITH SOIL CURRENTS 

Among the first experiments with soil currents on a large scale 
were those by Ross, prior to 1844, (44) in New York. He buried a 
copper plate 5 feet by 14 inches perpendicularly in the earth with 
the 5-foot edge horizontal, and at a distance of 200 feet a zinc plate 
of the same dimensions was similarly buried. The two plates were 
connected above the ground, forming a galvanic cell. Potatoes were 
drilled in rows between the plates and also in a similar plat without 
plates. At the end of the experiment some of the potatoes from both 
plats were measured, those from the treated plat averaging 2^2 
inches in diameter, while those from the control averaged only half 
an inch.* The total weights at harvest are hot given, and conclusive 
assurance that the two areas were of equal fertility at the outset is 
lacking. The supposed beneficial effect is rendered doubtful through 
the subsequent discontinuance of so simple a treatment. 

About this time Solly (46) conducted in England 70 small tests 
similar in principle to those of Ross, the plates being 4 by 5 inches 
and spaced only 6 inches apart. Grains, vegetables, and flowers 
were planted between the electrodes. On comparing the appearance 
of the treated and untreated plants a beneficial effect was recorded 
in 19 cases, a harmful effect in 16 cases, and no effect in 35 cases. 
Solly concluded that electricity has practically no effect on plant 
growth. 

Fitchner (16) has recorded large increases from treatment with 
galvanic currents. From his figures alone the experiments would 
indicate increases of 16 to 127 per cent due to treatment. The 
statement was made, however, that the treated plats were provided 
with drains but that the control plats were not. Such conditions do 
not constitute good experimental practice and leave the results open 
to question. This same objection holds for accompanying experi- 
ments on the decomposing action of the galvanic current on soil. 

62149 c 



18 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE 

In 1881, F. Elfving (15) undertook an interesting series of experi- 
ments with different seedlings growing in culture solutions through 
which he passed battery currents of different strengths. After 
germination the seedlings were mounted on corks which were floated 
in the solution between electrodes 6 by 4 centimeters in size. He 
found that in nearly every case the root would turn and grow in a 
direction against that of the electric current. Plates of carbon, 
zinc, and platinum were used, and all gave the same effect. Elfving 
attributes this phenomenon of orientation to the slowing up of the 
growth on the side of the root toward the positive pole. This same 
phenomenon was noticed by Plowman (40, 41) hi 1902-03. 

Holdefleiss (23) in 1884 selected several rows of sugar beets in a 
field which showed a good stand and uniform conditions. In this 
field copper plates 50 centimeters square were sunk perpendicularly 
in the ground 50 centimeters deep, so that the plates included two 
rows of beets. At the other end of the rows, 56 meters distant, 
other plates were sunk, and between the two a 14-cell Meidinger 
battery was connected. This same arrangement .was used on a potato 
field. Further experiments were conducted with copper and zinc 
plates 33 meters apart connected by a solid copper wire. The report 
of the experiments stated, in substance: 

(1) That an electric current was present on all treated plats throughout the 
season, its presence being determined by a sensitive electrometer; (2) that the 
rows of beets and potatoes between plates which were connected to the battery 
showed no difference in growth at any stage of their development; (3) that the 
beets and potatoes in rows between the zinc-copper combinations assumed a 
somewhat fresher and stronger appearance about 10 days after the beginning of 
the experiment, and the harvest showed an increased yield ranging from 15 to 
24 per cent. 

It should be remembered, however, that in experiments with soil 
currents the path of the current is not wholly by the most direct 
route from one electrode to the other, but that the lines of flow 
spread out through the soil in a way similar to the spreading of the 
lines of force between the poles of a bar magnet. 

Experiments conducted by Wollny (48) included five plats 4 by 1 
meter each in size separated by a path 1.2 meters wide and by boards 
sunk 25 centimeters in the ground. On plats 1 to 3 a zinc plate 
was sunk at both of the narrow sides, and these were connected as 
follows: Plat 1, induction coil operated by three Meidinger elements; 
plat 2, a battery of six Meidinger elements; plat 3, a battery of 
three Meidinger elements. On plat 4 a zinc plate was sunk on one 
end and a copper plate at the other, the two being connected above 
ground by a copper wire. Plat 5 constituted a check or control plat. 
Each plat was divided into four equal parts 1 square meter each 
in area and seeded. Numbers of plants up on different dates showed 
practically no effect for any of the different treatments. The yields 
recorded at harvest time, based on an equal number of plants per 
square meter, are shown in Table 20. 



ELECTROCULTURE 



19 



Table 20. — Yields of rye, rape, bean, and potato plants after electrocultural treat- 
ments in 1SS3, according to Wollny 





Treatment 


Yields per square meter (grams) 


Plat 


Rye, 
42 plants 


Rape, 

42 plants 


Beans, 
42 plants 


Potatoes, 
5 plants 


No. 1 Induction 


182.0 
219.8 

197.8 
201.6 
228.7 


114. 8 
94.5 
103.0 
114.7 
118.7 


517.5 
514.5 
420.0 
600.0 
631.0 


372 1 


No. 2 


6cells 


310.5 




3 cells 


315 3 


No. 4 


Cu-Zn 


397 8 


No. 5 


Control... _. _. 


377.6 













. These records show that in nearly all cases the control plat gave 
the best yields, but further experiments were conducted in 1886 and 
1887. The ground was well worked over, and four plats 16 by 2 
meters were selected, separated from each other by paths 1.2 meters 
wide and bordered by wooden lath walls. Each plat was divided 
into eight smaller plats 2 meters square and all were given equal 
applications of manure. On the small ends of the four large plats 
zinc plates 2 meters by 30 centimeters in area were sunk perpen- 
dicularly and connected above ground through an induction coil 
operated by 4 or 5 cells for plat 1 and through a 4 or 5 cell battery 
for plat 2. Plat 3 served as a control, and plat 4 had a copper plate 
at one end directly connected by a copper wire with a zinc plate at 
the other end. Diagonally lying plats were planted with the same 
crops, the grains being drilled to give a uniform planting. The 
presence of a current on all treated plats was noted by the use of a 
galvanometer. Throughout the season there was no perceptible 
difference in growth between treated and control plats during either 
year. The comparative-yield weights are shown in Table 21. 



Tabu: 21.- 



■Yields of vegetable crops after electrocultural treatments in 1886 and 
1887, according to Wollny 





Treatment 


Yields per plat 2 meters square (grams) 


Plat 


Rye 


Rape 


Peas 


Beans 


Corn 


Pota- 
toes 


Beets 


Tur- 
nips 


In 1886: 

No. 1 

No. 2 

No. 3 

No. 4 

In 1887: 

No. 1 

No. 2 


Induction 

."> cells 

Control 

Cu-Zn 

Induction 


113.3 
108.6 
107.8 
100.9 

933.0 
879.0 
948.4 
838.5 


339.0 
300.5 
405.8 
418.0 

775.0 
755. 
773.0 
761.6 


1,420.0 
1,570.0 
1,380.0 
1, 490. 

548.0 
588.0 
592.0 
571.0 


2, 040. 
2,410.0 
2, 220. 
2, 190. 

696.5 
607.0 
584.2 
465.0 


1,962.8 
1,923.6 
1,913.6 
2, 072. 9 


6,400 
4,650 
6,620 
6,670 

8,350 
8,190 
8,410 
8,920 


23,400 
24, 420 
28,100 
29,400 

19,640 
17, 650 
18,900 
16, 320 


22, 250 
18, 080 
21, 520 
20,800 

17,850 
18, 270 


No. 3... 

No. 4 


Control 

Cu-Zn. _. 


18, 460 
19, 660 



From these experiments Wollny concluded that an electrical cur- 
rent conducted through soil in which plants were growing had. in 
genera] no influence or possibly a harmful effect on the productive- 
ness of the plants. 

Leicester (29, 30) used boxes of soil 2)4 by 3 feet in area, with 
copper and zinc plates connected above ground. Control boxes 
without plates were included. After several trials with different 



20 BULLETIN 1379, U. S. DEPAETMENT OF AGRICULTURE 

kinds of seeds, it was found that in every case the seeds grew much 
quicker in the boxes containing the plate. Hemp seed was fully an 
inch above the surface before controls showed any plants. The 
observation was made also that plants in the zones nearest the plates 
were the first to come up. Watering with dilute acetic acid was 
found to cause quicker growth for treated plants— possibly because 
of increased current resulting from the acid-metal reaction. Upon 
repeating these experiments, Leicester decided that the only action 
of the current was to stimulate the plant until the initial store of 
food was used up. No data were recorded in either of his reports. 

Berthelot (3) conducted some tests with soil currents to determine 
whether electricity aided in the fixation of nitrogen by plants. Suit- 
able control plats were provided. He reported that the treated 
plants grew much more rapidly, being nearly twice the weight of 
the control plants at the end of four to six weeks. Although not 
complete or definite, the experiments were abandoned for various 
reasons. 

Kinney (27) made an extensive series of experiments to determine 
the influence of electrical currents on germination. Seeds were sub- 
jected to different current strengths for different periods of time and 
then put in suitable germination apparatus and the subsequent 
growth noted. An intermittent treatment of 30 seconds per hour 
was given in some cases, arranged by clock contacts. Two different 
arrangements were used for the treatments. In one a dass cylinder 
containing the seeds was equipped at each end with electrodes. 
These were pressed against the seeds through which the current Mas 
thus directly passed. In the other, the seeds were placed in wet 
sand held between perforated metal disks, which were used for the 
electrodes. The entire layer was held in a glass funnel in which the 
growth of the radicle could be measured without removal. Eight 
sets of 25 seeds eacli were used in each test, one set being the control 
and the other seven receiving different strengths of current. Experi- 
ments with barley showed that the growth of treated seeds increased 
as the current strength increased up to a certain optimum value, 
above which the growth decreased with increase in current strength. 
With white mustard, rape, and red clover the optimum treatment 
for both roots and stems was identical. 

Plowman (40, 41) has recorded the results of experiments con- 
ducted at the Harvard Botanical Gardens on the influence of soil- 
conducted currents on plant life. Platinum or carbon electrodes 
were used, with potentials ranging from 5 to 500 volts. The regu- 
lation of temperature was a serious difficulty — a fact mentioned for 
the first time in connection with such experiments and one that may 
have been ignored in earlier reports. Plowman found that seeds 
near the anode were always killed by a current of 0.003 ampere or 
more if continued for 20 hours. Seeds at the cathode were little 
affected by currents less than 0.08 ampere. 

Gerlach and Erlwein (19, 20), at Bromberg, investigated the 
effect of weak soil currents on germination and growth. The field 
was made up of seven plats of 200 square meters each. Current 
was taken from a car line and led to the three treated plats, which 
were provided with iron plates 20 meters long by 30 centimeters 
wide and 2 millimeters thick sunk into the soil at both ends. Each 
of the seven plats was seeded half with barley and half with potatoes. 



ELECTROCULTURE 21 

The treatment continued 24 hours a day for 86 days for barley and 
139 days for potatoes, beginning in April. Both barley and potatoes 
showed excellent growth, but no differences between the treated and 
control plats were discernible at any time. Other experiments 
were conducted with plants grown in boxes provided with copper 
and zinc plates connected overhead by wires. Trials with rye, 
wheat, anci lupine gave no difference between treated and untreated 
crops. 

Homberger (24) reported that the passage of high-frequency 
currents through the soil was beneficial to plant growth. His 
experiments were conducted on a small scale, using flowerpots with 
only a few plants, the treatment consisting of three applications 
daily until the temperature of the soil reached 35° C, when the 
current was cut off. The leaves and stems of the treated plants 
showed more chlorophyll than the controls. A photograph shows 
one pot each of treated and control plants, the treated plants being 
about five times as high as the others. In order to determine 
whether the heating was the main cause of increased growth another 
pot was subjected to test currents for five minutes daily. These 
plants were about four times the height of the controls when photo- 
graphed. From these comparisons Homberger concluded that the 
oscillating field and not the temperature was the main cause of the 
stimulation, and he believed his results to be due to chemical changes 
taking place under the influence of the oscillating electromagnetic 
field, analogous to the catalytic action of light. 

In 1907 (17) and 1909 (18) Gassner reported upon experiments 
with charged soil which indicated a general unfavorable action upon 
plant growth. 

Kovessi (28) obtained unfavorable results in researches involving 
some 1,100 experiments. 

Considerable publicity has been given to an apparatus called a 
"geomagnetifier," a sort of lightning rod designed to gather in 
atmospheric electrical energy and supply it to the crops. Among 
those who have reported favorable results through the use of such 
apparatus are Maccagno (35), Basty (2), and Paulin (39). 

At the present time methods of electroculture employing soil- 
conducted cm-rents have few proponents. 

EXPERIMENTS WITH MODIFIED POTENTIAL GRADIENTS 

Grandeau (21), in 1878, reported studies on the effect of the 
electrical condition of the atmosphere upon the growth of vegetation 
He grew plants in a Faraday cage consisting of four iron rods 1. 
centimeter in diameter by 1.5 meters high, holding fine iron wires 
forming 15 by 10 centimeter meshes. The cage was grounded in 
order to destroy the normal electrical field. Experiments were 
made with tobacco, corn, and wheat. The plants under the cage 
were reported weak and slender. Six stalks of wheat grown in 
free air weighed 6.57 grams, as compared with 4.95 grams for six 
stalks grown under the cage. 

Grandeau was led by these experiments to the belief that high 
trees act as a grounded network, in that they shield the vegetation 
beneath their foliage from the action of the normal electrical field, 
thereby causing a decreased rate of growth. With a sensitive 
Thompson electrometer, he compared the strength of the field in the 



22 BULLETIN 1379, U. S. DEPARTMENT OP AGRICULTURE 

open with that under vegetation. The results indicated that under 
trees and shrubs the potential gradient was greatly reduced. The 
experiments of Grandeau were confirmed by Mascart (36). 

As opposed to the conclusion of Grandeau, the modern greenhouse 
of steel construction constitutes in itself an approximation to a 
Faraday cage about the plants growing within it, and yet the develop- 
ment of the plants is surely not seriously impaired in consequence. 
Likewise, Briggs and Shantz (10, 11), in their investigation of the 
water requirements of plants, carried hundreds of pots of plants to 
full maturity under a grounded metal framework, covered above and 
on the sides with metal screen of ^-inch mesh, which must have 
annulled the normal electrostatic field; yet the plants grown within 
the inclosure were almost without exception superior in development 
and luxuriance of foilage to those grown in similar pots outside. 

Lemstrom (32) conducted in Finland a long series of experiments 
to determine, if possible, the influence of static electricity on plant 
growth. The presence of strong electric charges in the atmosphere 
of northern regions, as indicated by the northern lights, linked with 
the astonishing development of vegetation in such regions, led him 
to regard atmospheric electricity as an important factor in plant 
growth. Garden vegetables, fruits, and small grains were subjected 
to several different treatments in these investigations both in green- 
houses and in open fields. Lemstrom summarized the results of his 
experiments as follows: 

(1) The real increase due to electrical treatment has not yet been exactly 
determined for the different plants, but we are approaching its smallest value by 
fixing it at 45 per cent. 

(2) The better and more scientifically a field is cultivated and manured, the 
greater is the increase percentage. On poor soil it is so small as to be scarcely 
perceptible. 

(3) Some vegetables can not endure the electric treatment if they are not 
watered, but then they will give very high percentage increases. Among these 
are peas, carrots, and cabbage. 

(4) Electric treatment when accompanied by hot sunshine is damaging to 
most vegetables, probably to all; wherefore if favorable results are to be arrived 
at the treatment must be interrupted in the middle of hot and sunny days. 

Experiments similar to those conducted in Finland were conducted 
in England, Germany, and Sweden with like results. A detailed 
description of all of these experiments may be found in " Electricity 
in Agriculture and Horticulture," by Lemstrom (32). 

Priestley (42, 43) reported on the experiments of Newman (37) 
at Golden Valley Nurseries at Bitton. A small Wimshurst machine 
was used, one terminal of which was grounded and the other connected 
to wires suspended over outside plats and also to wires in seven glass- 
houses. The wires were hung 16 inches above the tops of the plants 
and were provided with discharge points hung at short intervals. 
The machine was operated 9.3 hours a day for 108 days between 
March 27 and July 26, the first half of the period in daytime and the 
latter half at night. Control plats were provided in all cases similar 
to the treated plats except without wires. The results recorded 
are given in Table 22. 



ELECTROCULTURE 



23 



Table 22.— Results of electrochemical treatment of garden crops at Bitton, as 

reported by Newman 



Crop 


Treated 
plants 


Notes 


Cucumbers, increase.. 


Per cent 
17 

36 
80 

15 


Less subject to bacterial disease. 


Strawberries: 

5-year plants, increase. 


1-year plants, increase. 


More runners produced. 
5 days earlier. 


Broad beans, decrease. 


Cabbage 


Celery, increase... 


2 


10 days earlier. 


Tomatoes (no difference). 




' 





During the same year an installation was working at Gloucester 
with higher voltage and wires 5 feet from the ground. The following 
TeS ^ L ath treated Plants were reported: Beets, 33 per cent increase 
and higher total sugar content; carrots, 50 per cent increase; turnips 
showed an increase, but the percentage was not recorded owing to 
slugs. 

In 1906 Newman (37) and Lodge (33), at Evesham, began some 
electro-culture experiments usmg about 40 acres, 20 of which were 
electrified with a network 15 feet above ground. The Lodge ap- 
paratus was used, 22 poles carrying the wire over the area, with small 
wires 12 yards apart. These experiments were continued several 
years. The results are summarized in Table 23. 



Table 23. 



-Results of electrochemical treatment of crops at Evesham in stated 
years, as reported by Newman 



Year and crop 



1906: 

Wheat (electrified area 12 acres)— 

Canadian, i ncrease 

English, increase 

1907: 

Wheat (electrified area 11 acres), in 

crease. 
Strawberries, increase.. 

1908: 

Wheat (electrified area 7.68 acres), in 
crease. 

Strawberries, decrease 

Tomatoes, increase . 

Cucumbers, increase 



Electri- 
fied 
crops 



Per cent 



29 
18 
25 

24.3 

9 
30 
8.4 



Notes 



Sold for iy 2 per cent higher price when bakers 
found it nroduced a better baking flour. The 
somewharpoor yield from the control plat was 
probably due to deficiency in lime, afterwards 
rectified. 



Estimated by cartloads. 



Dry season. 

By weight per plant (average). 

By number (average). 



Newman reported later (38) that during seven successive years 
(1905 to 1911) wheat gave an average increase of 21 per cent in weight 
of grain and an increase of straw which it was not possible to measure. 

Potato variety experiments conducted at Dumfries, Scotland, by 
Dudgeon in 1911 and 1912 (14) gave the yields shown in Table 24. 



24 



BULLETIN 1379, IT. S. DEPARTMENT OF AGRICULTURE 



Table 24. — Results of electrocultural treatment of potato varieties at Dumfries, 
Scotland, by Dudgeon in 1911 and 1912 



Variety 


Yield (tons) 


Variety 


Yield (tons) 


Treated 


Control 


Treated 


Control 




8.05 
11.72 


5.85 
9.88 


Golden Wonder 


8.74 
11. 79 


8. 12 






10.31 









In 1912 further experiments at Dumfries were carried on in another * 
field, exposed to wind from any quarter. Two corners of the 4 
acres were treated, the others left as controls. No difference in 
yield was recorded, and it is explained that probably all plats are to 
be regarded as treated plats. 

In 1915 Dudgeon conducted an experiment with oats. The crop 
was grown on ground that had been used for similar experiments 
on potatoes for three years. Two adjacent plats of 1J^ acres each 
were separated by a well-grounded wire screen 3 feet higher than the 
charged network. A sensitive electrometer showed that the screen 
reduced the leakage over the control plat but did not altogether 
prevent it. The season was dry and the crop was not heavy. From 
early stages the treated plat showed a marked superiority in com- 
parison with the control, and did not suffer from the prevailing 
drought to the same extent. The electrical discharge was applied 
about five hours each day for 108 days. The weights (pounds) 
recorded at harvest were as follows: Treated — grain, 1,309, straw 
2,476; control— grain 1,008, straw 1,572. 

These figures indicate an increase of about 30 per cent in grain 
and about 58 per cent in straw. Analyses of the grain from the two 
plats show T ed practically no difference in quality. 

Blackman and J0rgensen (6) have also reported experiments by 
Dudgeon at Dumfries, Scotland, with oats. In a 9-acre field 1 acre 
was selected for treatment and two half-acre plats for controls. 
The distance between the silicon-bronze wires of the network was 4.5 
yards. Current of 3 amperes at 50 volts was supplied to the primary 
circuit, giving a greater intensity of discharge than that obtained 
in the experiments of the previous years. The discharge was started 
just as soon as the crop appeared above ground, and within a month 
a marked difference was noted. The treated plants had deeper color 
and were higher than the control plants. Throughout the season the 
treated crop w T as 5 to 10 inches higher than the control. Plants 
around the network also showed the effect of the discharge. The 
total application from April 14 to August 17, daytime only, was 848 
hours. Heavy rains did a good deal of damage. The comparative 
yields were as shown in Table 25. 



Table 25. — Results of electrochemical treatment of oats at Dumfries, Scotland, by 
Dudgeon, as reported by Blackman and Jfirgensen 




Yields (pounds) 


Field 


Grain 


Straw 




Quality 1 


Quality 2 


Bunches 


Total 


Per bunch 


Control 1 (half acre) 


630 

1,942 
714 


210 
695 
210 


99 
316 
103 


1,218 
4,924 
1,401 


12.3 


Treated (acre) 


15.6 


Control 2 (half acre) 


13.6 







ELECTROCULTURE 



25 



These results indicate a 49 per cent increase in grain and an 88 per 
cent increase in straw for the electrical treatment. 

The Liverpool City and Electrical Engineers reported on experi- 
ments conducted near Liverpool, England, in 1917. Two plats in 
newly plowed pasture land separated by about 375 feet were used, 
an analysis indicating that the surface and subsoil were of the same 
character. Various plant crops were grown, and in general the elec- 
trified area gave substantial increases in yield over the control area. 
A copy of this report is on file in the Office of Biophysical Investi- 
gations, Bureau of Plant Industry. 

Honcamp (25) has summarized the results of several previous in- 
vestigations and pointed out serious objections to the methods used. 

Table 26. — Results of electrochemical treatments of oat crops at Mocheln, Germany, 
according to Gerlach and Erlwein 



Electrical and soil treatment 



Relative yields 



Grain 



Straw 



Composition (per cent) 



Grain 



Dry mat- 
ter 



Nitrogen 



Straw 



Dr y e mat " Nitrogen 



No electricity: 

Fertilizer, irrigation 

Do 

Fertilizer, no irrigation. 

Do 

No fertilizer, no irrigation __ 

Do 

Direct current: 

Positive, fertilizer, irrigation 

Negative, fertilizer, irrigation 

Positive, fertilizer, no irrigation 

Negative, fertilizer, no irrigation 

Positive, no fertilizer, no irrigation. 
Negative, no fertilizer, no irrigation 
Alternating current: 

Fertilizer, irrigation 

Do 

Fertilizer, no irrigation 

Do 

No fertilizer, no irrigation 

Do._ 



26.60 
28.80 
20.60 
20.90 
19.60 
19.60 

27.80 
27.80 
21. 60 
20.50 
21.00 
17.80 

26.20 
26.00 
19.50 
19.90 
18.00 
18.00 



34.40 
32.20 
24.40 
22.10 
19.40 
17.40 

36.20 
37.20 
24.40 
22.50 
23.00 
18.20 

31.80 
32.00 
21.50 
21.10 
18.00 
18.00 



91.4 
92.4 
87.9 
89.9 
90.4 
90.1 

90.4 
91.7 
90.5 
91.2 
84.4 
90.4 

91.7 
90.6 
91.3 
89.8 
91.1 
91.4 



1.94 
1.70 
2.13 
2.04 
1.85 
1.67 

1.94 
1.74 
2.16 
2.07 
1.88 
1.72 

1.81 

1.78 
2.16 
2.11 
1.84 
1.83 



77.4 
76.2 
73.5 
74.3 
78.8 
79.8 

71.6 
72.9 
74.5 
73.7 
76.6 
78.4 

78.4 
77.9 
73.2 
75.9 
82.2 
85.0 



0.32 
.27 
.46 
.38 
.32 
.32 

.27 
.24 
.36 
.30 
.28 
.28 

.28 
.23 
.33 
.30 
.28 
.26 



Summary of Relative Yields of Grain and Straw 



Soil treatment 



No elec- 
tricity 



High-tension current 



Direct 



Positive Negative 



Alter- 
nating 



Grain: 

No fertilizer, no irrigation 
Fertilizer, no irrigation... 
Fertilizer, irrigation 

Straw: 

No fertilizer, no irrigation 
Fertilizer, no irrigation.. _ 
Fertilizer, irrigation 



19.60 
20. 75 
27.70 

18.40 
23.25 
33.30 



21.00 
21.60 
27.80 

23.00 
24.40 
36.20 



17.80 
20. 50 
27.80 

18.20 
22.50 
37.20 



18.00 
19.70 
26.10 

18.00 
21.30 
31.90 



On the Continent during this period many electrocultural experiments 
were carried out, using networks charged to high potentials. Reports by 
Hostermann (22), Gerlach and Erlwein (19, 20) , Clausen (13) , Breslauer 
(9) , and others indicate that no benefit may be expected from the use 
of the network. The German experiments made use of an extensive 



26 



BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE 



and variable complex of conditions, designed to include the study of 
positive and negative potential in relation to fertilizers and irrigation 
and the relation of these factors to the composition of grain and straw. 
The results shown by Gerlach and Erlwein reporting experiments 
with oat crops at Mocheln are selected as representative. (Table 26.) 

It may be well worth while to consider Table 26 in some detail, 
since it seems to represent a thoroughly impartial study of the 
methods which have given success elsewhere.- 

The instances in which duplicate trials were run and the agree- 
ments to be noted for these cases show rather conclusively that lack 
of uniformity in soil conditions was not a disturbing factor in these 
experiments. The six plats giving notably higher yields are those 
with fertilizer and irrigation. These are in good agreement and show 
no appreciable advantage for the three types of electrical treatment 
represented, the averages for relative yields only being as shown in 
the summar}^ of Table 26. 

The plats in these experiments were about one-fourth acre each, 
the control plats being separated from the electrified plats by about 
325 feet. The potential of the direct-current network was about 
30,000 volts, whereas that of the alternating current was about 
20,000 volts. The statement of Lemstrom that the better the con- 
dition of the field the more favorable the influence of the high-tension 
discharge is not substantiated by these trials. In brief, the German 
experiments give little evidence of any definite crop increase at- 
tributable to the electrical treatment. 

In 1913 Dorsey conducted greenhouse experiments in Ohio with 
radishes and lettuce, using a high-frequency current. In a letter to 
Doctor Briggs dated August 1 8, 1 913, he reported the relative weights 
of 10 plants selected at random from each area. These are shown in 
Table 27. 



Table 27. — Results of electrocultural treatments of greenhouse radishes and lettuce 
in 1913, according to Dorsey 





10 plants 


Relative weights (grams) 




Radishes 


Lettuce 




Treated 


Control 


Treated 


Control 


Total 


265. 7 
(39.5 

120.5 
9.3 


ISO. 

7(1.4 

95.0 

5.6 


67.0 
60.7 


46.1 


Edible portion 


41.8 


Tops , 




Roots 


6.3 


4 3 







Dorsey also conducted field trials with a high-frequency current. 
The plants used were beets, lettuce, cabbage, beans, melons, cucum- 
bers, and tobacco. They were planted in long rows, one-half of each 
row being under the charged network. The treated plat covered 
about half an acre. The network was 9 feet above ground with wires 
15 feet apart and carried a voltage of about 50,000 at an estimated 
frequency of about 30,000 cycles. The power was taken from a 
7% kilowatt 220-volt transformer supplying 11,000 volts at 60 
acycles and exciting an oscillating circuit containing the network as 
capacity. Treatment was given daily, three hours in the forenoon 



ELECTROCULTURE 



27 



and three hours in the afternoon. A generally favorable influence for 
the discharge treatment was reported. Unfortunately total weights 
were not included. The results for the second year were generally 
unfavorable for the discharge treatment, and Dorsey concluded that 

Eerhaps slight differences in the slope of the two plats may have 
een responsible for the favorable results of the first year. 5 
At the present time perhaps the best evidence of plant response to 
electrical discharge is that obtained by Blackmail (4, 5, 6, 7, 8) 
of the electroculture committee of the British Ministry of Agricul- 
ture and Fisheries. His experiments extend over a period of years 
and comprise field trials, pot cultures, and laboratory tests, all of 
which he interprets as affording converging evidence for a favorable 
growth response to the application of electricity. On account of the 
practical possibilities associated with a treatment assuring increased 

growth it seems desirable to examine in some detail the data which 
ave given rise to this assurance. 
The field trials carried on in England by Blackman and his as- 
sociates have given the results which are summarized in Table 28. 

Table 28. — Results of electrocultural treatments of grain crops in England, as 
reported in field experiments by Blackman 



Crop and year 


Location 


Acreage 


Duration 
of treat- 
ment 
(hours) 


Yield per acre 
(bushels) 


Ratio of 
treated to 




Treated 


Control 


Treated 


Control 


control 


Oat: 
















1915.. 




1.5 


1.5 


557 


20 7 


16 


1 29 


1916 


do 


1.0 
.33 


1.0 

.33 


848 
1,060 


62.8 
54.8 


42.0 

48.9 


1 49 


1917... 


do _ 


1.12 


1917 


do.... 


.33 


.33 


1,060 


42 2 


44 9 


93 


1917- . 


do 


.33 


.33 


1,060 


36 9 


38 1 


96 


1918... 


do _...'. 


.25 


.06 


704 


75.5 


56.1 


1.34 


1918 


do 


.25 


.06 


704 


84.9 


58.4 


1.45 


1918 .. 




.25 


.06 


704 


80 4 


46 3 


1 73 


1919 


do 


.11 


. 11 


710 


36.6 


45.2 


.80 


1919 


do 


.11 


.11 


710 


45.1 


43.8 


1.02 


1919 


do 


. 11 


. 11 


710 


53 3 


28 9 


1 84 


1919.. 


Harper Adams Agricul- 
tural College. 


.50 


.33 


456 


47.0 


53.6 


.87 


1919 


do 


.25 


.33 


456 


63.8 


48.2 


1.32 


1919 


do 


.25 




456 


50.8 


48.2 


1.05 


1919 


...do 


.50 


.33 


456 


60.2 


59 6 


L01 


1920 


Lini'luden 


.11 


. 11 


911 


36.2 


44.8 


.80 


1920. 


do 


. 11 


.11 


911 


43.5 


46.1 


.94 


1920 


do 


.11 


.11 


911 


51.8 


33.0 


1.56 


1920 


Harper Adams Agricul- 
tural College. 


.33 


.33 ? 


793 


50.0 


56.0 


.89 


1920 


do 


.33 




793 


52.5 


56.0 


.93 


Barley: 
















1917. 


Rothamsted 


. 0125 


.0125 


1,500 


17.8 


13.1 


1.36 


1918 


do 


.66 


.10 


643 


44.7 


36.4 


1.22 


1918.. 


do 


.66 


.10 


643 


47.4 


52.7 


.89 


1918 


do 


.66 


. 10 


643 


40.4 


36.3 


1.11 


1920 


do.. 


.50 


.50 


786 


31.7 


29.5 


1.07 


1920 


do 


.50 


.50 


786 


33.0 


25.17 


1.31 


Winter wheat: 
















1919 


do. 


.50 


.50 


854 


21.4 


14.3 


1.49 


1919 


do 


.50 


.50 


854 


22.3 


17.4 


1.28 


1920 


...do 


.25 
.25 


.25 
.25 


727 
727 


18.84 
18.35 


20.4 
18.24 


.92 


1920 


do 


1.006 


Spring wheat: 






1919 


do 


.50 


.33 


940 


7.6 


10.0 


.76 


1919 


do 




.33 


940 


} 7.3 


/ 7.9 


.92 


1919 


...do 


.50 


.33 


940 


\ 6.3 


1.15 










1.14 



















s Correspondence with the Office of Biophysical Investigations, Bureau of Plant Industry, September 
2, 1924. 



28 



BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE 



These tabulated values are in many ways not subject to biometrical 
analysis; they represent the results of experiments carried out with 
varied complexes of soil, season, acreage, crop, and electrical treat- 
ment. Nevertheless, in the absence of any definite knowledge con- 
cerning the conditions under which an electrical treatment may be 
presumed to be most effective there is perhaps no better index than 
a comparison. 

Of 33 trials shown in Table 28, 21 indicate an increase for treated 
areas, whereas 12 indicate a decrease. The treated areas return a 
yield represented by the range 76 to 184 when the untreated areas 
return a yield represented by 100 and give an average increase of 
14 per cent. This increase is based upon yields reported for experi- 
ments regardless of crop or seasonal normality, and Blackman esti- 
mates the more reliable experiments as indicative of an average 
increase in yield of about 22 per cent. In either case, such an in- 
crease would seem sufficient to be of promise from an agricultural 
standpoint. If an attempt is made to determine from these tabu- 
lated values the conditions under which the increases were obtained, 
serious difficulties are immediately encountered. 

Unfortunately the normal productivity of the electrified and 
control areas is in most cases unknown, and a serious lack of soil 
uniformity is evident from the yields of different portions of control 
areas. For example, in the 1919 and 1920 plats with oats at Lin- 
cluden, which occupied the same areas for the two years, the control 
yields were as shown in Table 29, in which the relative yields of the 
corresponding treated areas for the same years, the controls being 
taken as 100, are also shown for comparison: 



Table 29. 


— Comparison of the results of electrocultural experiments with oat crops 
at Lincluden, England, in 1919 and 1920 




Area 


Acre yields of control 
plats (bushels) 


Relative yields of elec- 
trified areas, the con- 
trols being taken as 
100 




1919 


1920 


1919 


1920 




45.2 
43.8 
28.9 


44.8 
46.1 
33.0 


80 
102 
184 


80 


II 


94 


in 


156 







It is obvious that the yields of the third section of the control 
area were uniformly low compared with the yields of the other 
control sections and that this fact is almost certainly involved in 
the high percentage increases arising for the third section of the 
t reated area. It would therefore appear that these particular 
increases may be attributed to a lack of soil uniformity, and the 
importance of this unknown factor is indicated. 

The most consistent series indicating favorable response to electrical 
treatment appears to be the 1918 oat trials at Lincluden. The plats 
in oats at Lincluden gave the average annual yields shown in Table 
30. 

The yields from the electrified areas in 1918 seem to have been 
so exceptional compared with the electrified areas for the three 
other years that one may question whether it is justifiable to attri- 
bute the increase solely to the electrical treatment. 



ELECTBOCULTUEE 



29 



Table 30. — Analysis of the average results of electrical treatments of oat plats at 
Lincluden, England, in the years 1917 to 1920, inclusive 





Year 


Average acre yields 
(bushels) 


Ratio of 

treated to 

control 


Year 


Average acre yields 
(bushels) 


Ratio of 
treated to 




Treated 


Control 


Treated 


Control 


control 


1917 


44. 6 44. 
80. 2 53. fi 


1.01 
1.49 


1919.. 
1920. 




45.0 
43.8 


39.3 
41.3 


1.14 


1918 




1.06 













The instances specifically considered in Tables 29 and 30 comprise 
the most notable of the percentage increases reported by Blackmail, 
as shown in Table 28, and they are therefore in a large measure the 
basis of the 22 per cent average increase reported. One is thus left 
without definite assurance that the field experiments demonstrate 
a favorable response to the electrical treatment. 

The pot-culture experiments in England by Blackman and his 
associates gave results which are summarized in Table 31. 

Table 31. — Results of electrical pot-cidture experiments with grain crops in Eng- 
land, according to Blackman 



Year and crop 


Yields (grams) 


Ratio of 
treated to 

control 


Year and crop 


Yields (grams) 


Ratio of 

treated to 

control 


Treated 


Control 


Treated 


Control 


1918: 

Wheat 


/ 0.72 

\ -71 

1.43 

1.21 

1.24 

2. •_'<; 

2.12 

1.98 

.97 

1. 17 

1.12 

8.12 

8.37 

7.41 

10.84 

10.36 

10. 85 

f 5. 70 
6.81 
2.52 
16.73 
16.03 
15.01 
13. 72 
15.84 
11.75 


} 0. 73 
I 1.39 

\ 2.30 

I 1.29 

[ 7.78 

1 8.54 

5.62 
5.67 
2.32 

1 17.28 

\ 18. 69 
16.89 


i ' 0. 98 
1 .97 
f 1.02 
\ .87 

.89 
f .98 
\ .92 

.86 

.75 
\ .90 

.86 

1.04 

I 1.07 

.95 
| 1.26 
I 1.21 
I 1.27 

1.01 

1.20 

1.08 

f .96 

\ .92 

.86 

I .73 

\ .84 

.69 


1920: 


/ 15. 66 
\ 15. 39 
1 23. 84 

23.28 
\ 26.33 

17.66 
\ 17. 11 
I 18. 76 

f 10.60 
11.79 
34.0 
37.2 
49.2 
53.0 
48.5 
51.9 
22.8 
15.5 
14.27 
18.20 
18.95 


}• 14. 52 
I 23.88 

I 16. 22 

} 10. 29 
} 31.5 

1 46.5 

21.2 
| 15.6 

| 16. 60 


f 1.07 
\ 1.05 
1 .99 
} .97 




Barley 




Wheat.. 


J 1.10 
f 1.08 
< 1.05 




1921: 


I 1.15 




/ 1.03 
\ 1.14 
/ 1.07 
\ 1.18 
f 1.05 


1919: 

Maize 


Maize 


1.13 
1 1.04 
I 1.11 

1.07 
/ .99 
\ .91 
/ 1.09 
\ 1.14 




1.01 

















As with the tabulated values for field experiments, so here also the 
results of the pot-culture trials represent more than the electric dis- 
charge variable; soil and seasonal factors vary as well as the crop 
and the duration, nature, and strength of the electrical treatment. 
Making a comparison, 26 trials out of 47 give positive results, while 
21 give negative results. The treated plants return yields repre- 
sented by the range 73 to 127; when the untreated plants return a 
yield represented by 100 and give an average increase of 1 per cent. 
This increase is well within the experimental error, and the pot- 
culture trials in their entirety thus furnish no definite evidence of a 
response to the electrical treatment. 



30 



BULLETIN 1370, U. S. DEPARTMENT OF AGRICULTURE 



In contrast to the field experiments, however, the pot-culture trials 
afford results from several similarly treated pots and plants, so that 
an estimate of individual experiments may be made by comparing 
the differences between treated and untreated plants with the prob- 
able errors involved in the measurements. 

When the pot-culture records are examined in this way, it becomes 
evident that the treated and untreated plants present substantial 
differences. With uniform soil and seasonal factors for electrified 
and control plants the association of these differences with the 
treatment becomes intimate. The fact that these differences favor 
the control plants about as often as the treated plants emphasizes 
the complexities involved and makes one less certain that these 
differences are definitely attributable to the electric discharge. 

The laboratory experiments of Blackmail and his associates have 
been on the effect of a direct current of very low intensity on 
the rate of growth of the coleoptile of barley. Differences in the 
growth rate of treated and control plants were noted over short 
periods. The small differences attributable to the direction of the 
current and the pronounced after effects obtained make the inter- 
pretation of the data difficult and uncertain. 

In general, then, one finds in Blackman's experiments many 
significant differences between the electrified and control plants. 
In some instances the relation of the discharge to these differences 
may well be questioned. In others the relation appears to be an 
intimate one. and the significance of such differences is the immediate 
concern of further research in electroculture. 

Table 32. — Summary of elcctrocultural trials 



1 


Definite influence reported 


\o definite influence reported 


Method 


Year 


Observer 


Year 


Observer 


Soil-conducted currents: 


(1889 
J 1892 
11897 
1 1902 
[1892 
{1903 
U914 
(I860 
OS84 
(1844 
1916 

fl904 
1905-1911 
1913 
1914 

1917 

[1876 
1878 
1910 




1893 
1899 
1902 
1905 
1S46 


Bmttini. 






Ahlfvengren. 


Germination 










Lowenberg. 




W arner 

Stone 


Solly. 














1883-87.. 

1907 

1909 


Wollnv. 




Holdefleiss 


Gassner. 






Gerlaeh and Erlwein. 


Soluble plant food 

Modified atmospheric po- 
tential gradient: 
















1907 

1909 

1909-1910 

1910 

1911 

1918-1924 

1880 
1914 


Gassner. 




Dorse v ______ 


Gerlaeh and Erlwein. 


Increased potential 


Jorgensen, Priestley, 
Dudgeon. 

Blackman, Liverpool en- 
gineers. 


Breslauer. 

Hostermann. 

Clausen. 

Briggs, Campbell, Heald, 

Flint. 
Laikewicz. 






Briggs and Shantz. 

















A review of the literature of elcctrocultural experimentation up 
to the present time does not lend assurance of great progress. (Table 
32.) In 1800 Senebier (4-5) wrote substantially as follows: 









ELECTROCTJLTTJRE 31 

The researches of Maimbray, Nollet, Bose, Menon, and Jalabert would 
indicate that electricity accelerated the development of plants, both in their 
germination and in their subsequent development. Nuneberg, many years 
afterward, repeated the same experiments with the same results. Linne and 
Kostling observed the same effects. Achard confirmed these results. Berthelon, 
in a treatise on the electricity of plants, has summarized the information on the 
subject and substantiated it by further research of his own. Gardini, from work 
carried on at Lyon, affirmed the influence of electricity on vegetation. Carmoy, 
d'Ornoy, and Rosieres have defended this opinion in the Journal de Physique. 
These doctors base their conclusions on the identity of natural and artificial 
electricity, on the continual electrified condition of the atmosphere, and on the 
meteorological phenomena which indicate in a more or less sensitive manner 
the presence of electricity; the different elevated parts of plants, which are in 
themselves excellent conductors of electricity, offer in their leaves, as De Saussure 
has observed, the proper points to receive the electric fluid. . . . All these 
experiences led to the opinion stated when Ingenhousz published experiments 
which proved that electricity would not produce the effects upon plants which 
had been attributed to it; that electrified seeds 6 would not germinate quicker 
than others. These experiments, reported in the Journal de Physique for 
December, 1785, were confirmed in the same journal for December, 1786, were 
given further support in May, 1788, and were finally summarized in "Experi- 
ences sur les vegetaux." Various other workers later confirmed these re- 
searches. It seems to me at present [1S00] that the opinion of those who believe 
that electricity does not favor vegetation is more logical than the contrary 
opinion. 

At the present time (1924), there is still a diversity of opinion 
concerning the influence of electricity in plant development. The 
electroculture committee of the British Ministry of Agriculture and 
Fisheries recommends (1923) the continuation of experiments with 
high potential discharge, 7 Newman (3S) in England considers 
electroculture by the same method as offering practical assurance 
of increased returns. Baines (1) points out a wonderland of electro- 
biological relationships. On the other hand the experiments of 
Gerlach and Erlwein (19, 20) in Germany and the experiments 
reported in the first part of this bulletin show no increased growth 
definitely attributable to electrical treatment. 

• Leighty and Taylor ( 31 ) report experiments with electrified seed which indicate no advantage gained 
by treatment. 
7 Typewritten report on file in the Office of Biophysical Investigations, Bureau ot Plant Industry. 



LITERATURE CITED 

(1) Baines, A. E. 

1921. Germination in its electrical aspects. 185 pp., lllus. London 
and New York. 

(2) Basty F. 

1908. Essais d'electroculture tentes a Angers en 1908. (Extrait.) In 
Bui. Soc. Etudes Sci. Angers, aim. 37 (1907), pp. 87-92. 

(3) Berthelot, M. 

1889. Recherches nouvelles sur la fixation de 1 Azote par la terre 
vegetale. Influence de l'electricite. In Compt. Rend. Acad. 
Sci. [Paris], tome 109, pp. 281-287. 

(4) Blackman, V. H. „.,.., 

1918-1924. [Electrical treatment of fields.] Gt. Brit. Mm. Agr. and 
Fisheries Interim Rpts. 1-6 (1917-23). [Mimeographed.] 

(5) 1924. Field experiments in electro-culture. In Jour. Agr. Sci., vol. 14 

(1923), pp. 240-267. 

(6) and J0rgensen, I. 

1917. The overhead electric discharge and crop production. In Jour. 
Bd. Agr. [London], vol. 24, pp. 45-49, illus. 

(7) and Legg, A. T. 

1924. Pot-culture experiments with an electric discharge. In Jour. 
Agr. Sci., vol. 14, pp. 268-286, illus. 

(8) and Gregory, F. C. 

1923. The effect of a direct electric current of very low intensity on the 
rate of growth of the coleoptile of barley. In Proc. Roy. Soc, 
London, ser. B, vol. 95, pp. 214-228, illus. 

(9) Breslatjer, M. . . 

1912. Amount of energv needed for electro-culture. In Electrician, 

vol. 69, pp. 889^890. 

(10) Briggs, L. J., and Shantz, H. L. 

1913. The water requirement of plants. I. U. S. Dept. Agr., Bur. 

Plant Indus. Bui. 284, 49 pp., illus. 

(11) 1914. Relative water requirements of plants. In Jour. Agr. Research, 

vol. 3, pp. 1-63, illus. 

(12) Chree, C. 

1910. Atmospheric electricity. In Enc. Brit., vol. 6, pp. 860-870, 

illus. 

(13) Clausen. 

1911. Die Erfolge der Elektrokultur in Hedewigenkoog. In Landw. 

Wchnbl. Schles.-Holst., Jahrg. 61, pp. 83-86. 

(14) Dudgeon, E. C. 

[1912]. Growing crops and plants by electricity. 36 pp., illus. 
London. 

(15) Elpving, F. 

1882. Ueber eine Wirkung des galvanischen Stromes auf wachsende 
Wurzeln. In Bot. Ztg., Jahrg. 40 (1881), pp. 257-264, 273-278. 

(16) Fitchner, E. 

1861. Agronomische Zeitung, 1861, p. 550. [Not seen. Reference 
from Bruttini, A., L' influenza dell' elettricita sulla vegeta- 
zione, p. 148, Milano, 1912.] 

(17) Gassner, G. 

1907. Zur Frage der Elektrokultur. In Ber. Deut. Bot. Gesell., Bd. 
25, pp. 26-38, illus. 

(18) 1909. Pflanzenphysiologische Fragen der Elektrokultur. In Mitt. 

Deut. Landw. Gesell., Jahrg. 24, pp. 5-7. 

32 



ELECTROCUL.TURE 33 

(19) Gerlach, M., and Erlwein, G. 

1910. Versuche ueber Elektrokultur. In Elektrochem. Ztschr., Jahrg. 
17, pp. 31-36, 66-68, illus. 

(20) 1910. Versuche iiber die Einwirkung der Elektrizitat auf das Pflanzen- 

wachstum. In Mitt. K. Wilhelms Inst. Landw. Bromberg, 
Bd. 2, pp. 424-453, illus. 

(21) Grandeau, L. 

1878. De l'influence de l'electricite atmospherique sur la nutrition des 
plantes. (Extrait.) In Compt. Rend. Acad. Sci. [Paris], 
tome 87, pp. 60-62, 265-267, 939-940. 

(22) HOSTERMAN.N. 

1910. Geschichte und Bedeutung der Elektrokultur unter Beruck- 
sichtigung der neueren Versuche. In Arch. Deut. Landw., 
Jahrg. 34, pp. 535-570. 

(23) HoLDEFLEISS. 

1885. Elektrische Kulturversuche. In Centbl. Agr. Chem., Jahrg. 14, 
pp. 392-393. 

(24) HOMBERGER, E. 

1914. Behandlung von Pflanzen mit Hochfrequenzstromen. In 
Umschau, Jahrg. 18, pp. 733-735, illus. 

(25) Honcamp, F. 

1907. Die Anwendung der Elektrizitat in der Pflanzenkultur. In 

Fiihling's Landw. Ztg., Jahrg. 56, pp. 490-499. 

(26) J0rgensen, I., and Priestley, J. H. 

1914. The distribution of the overhead electrical discharge employed 
in recent agricultural experiments. In Jour. Agr. Sci., vol. 6, 
pp. 337-348, illus. 

(27) Kinney, A. S. 

1897. Electro-germination. Mass. Hatch Agr. Exp. Sta. Bui. 43, 
32 pp., illus. 

(28) Kovessi, F. 

1912. Influence de l'electricite a courant continu sur le developpement 
des plantes. In Compt. Rend. Acad. Sci. [Paris], tome 154, 
pp. 289-291. 

(29) Leicester, J. 

1892. The action of electric currents upon the growth of seeds and 
plants. In Chem. News (London), vol. 65, p. 63, illus. 

(30) 1892. Action of an electric current upon the growth of seeds. In 

Chem. News (London), vol. 66, p. 199. 

(31) Leighty, C. E., and Taylor, J. W. 

1924. Electrochemical treatment of seed wheat. U. S. Dept. Agr. 
Circ. 305, 7 pp., illus. 

(32) Lemstrom, S. 

1904. Electricity in agriculture and horticulture. 72 pp., illus. 
London and New York. 

(33) Lodge, O. 

1908. Electricity in agriculture. In Nature, vol. 78, pp. 331-332, 

illus. 

(34) 1911. The mode of conduction in gases illustrated by the behaviour 

of electric vacuum valves. In Phil. Mag. and Jour. Sci., 
ser. 6, vol. 22, pp. 1-7, illus. 

(35) Maccagno, J. 

1880. Influenza dell' elettricita atmosferica sulla vegetazione della 
vite. In Staz. Sper. Agr. Ital., vol. 9, pp. 83-89. 

(36) Mascart, E. E. 

1876. Traite d' electricite statique. 2 vol., illus. Paris. 

(37) Newman, J. E. 

1911. Electricity as applied to agriculture. In Electrician, vol. 66- 
pp. 915-916, illus. 



34 BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE 

(38) 1922. Electricity and plant growth. In Standard handbook for 

electrical engineers, Ed. 5, pp. 1810-1811. New York. 

(39) Paulin. 

1892. De 1' influence de l'electricite sur la vegetation. Montbrison. 
[Not seen. Reference from Bruttini, A., L'influenza dell'- 
elettricita sulla vegetazione, p. 216. Milano. 1912.] 

(40) Plowman, A. B. 

1902. Certain relations of plant growth to ionization of the soil. 
In Amer. Jour. Sci., ser. 4, vol. 14, pp. 129-132, illus. 

(41) 1903. Electromotive force in plants. In Amer. Jour. Sci., ser. 4, 

vol. 15, pp. 94-104, illus. 

(42) Priestley, J. H. 

1907. The effect of electricitv upon plants. In Proc. Bristol Nat. 
Soc, ser. 4, vol. 1 (1906), pp. 192-203. 

(43) 1910. Overhead electrical discharges and plant growth. In Jour, 

Bd. Agr. [London], vol. 17, pp. 16-28. 

(44) Ross, W. 

1844. Galvanic experiments on vegetation. U. S. Comr. Patents 
Rpt., vol. 27, pp. 370-373, illus. 

(45) Senebier, J. 

[1800.] Physiologie vegetale. 5 vols. Geneve. 

(46) Solly, E. 

1846. The influence of electricitj^ on vegetation. In Jour. Hort. Soc. 
London, vol. 1 (1845), pp. 81-109. 

(47) Wilson, C. T. R. 

1923. Atmospheric electricity. In Glazebrook, R., A dictionary of 
applied physics, vol. 3, pp. 84-107, illus. 

(48) Wollny, E. 

1888-1893. Elektrische Kulturversuche. In Forsch. Agr. Phys., 
Bd. 11, pp. 88-112, 1888; 16, pp. 243-267, 1893. 



ORGANIZATION OF THE 
UNITED STATES DEPARTMENT OF AGRICULTURE 

December 2-2, 1925 



Secretary of Agriculture W. M. Jardine. 

Assistant Secretary R. W. Dunlap. 

Director of Scientific Work 

Director of Regulatory Work Walter G. Campbell. 

Director of Extension Work C. W. Warburton. 

Director of Information Nelson Antrim Crawford. 

Director of Personnel and Business Adminis- 
tration W. W. Stockberger. 

Solicitor R. W. Williams. 

Weather Bureau Charles F. Marvin, Chief. 

Bureau of Agricultural Economics Thomas P. Cooper, Chief. 

Bureau of Animal Industry John R. Mohler, Chief. 

Bureau of Plant Industry William A. Taylor, Chief. 

Forest Service W. B. Greeley, Chief. 

Bureau of Chemistry C. A. Browne, Chief. 

Bureau of Soils Milton Whitney, Chief. 

Bureau of Entomology L. O. Howard, Chief. 

Bureau of Biological Survey E. W. Nelson, Chief. 

Bureau of Public Roads Thomas H. MacDonald, Chief. 

Bureau of Home Economics Louise Stanley, Chief. 

Bureau of Dairying C. W. Larson, Chief. 

Fixed Nitrogen Research Laboratory F. G. Cottrell, Director. 

Office of Experiment Stations E. W. Allen, Chief. 

Office of Cooperative Extension Work C. B. Smith, Chief. 

Library Claribel R. Barnett, Librarian. 

Federal Horticultural Board C. L. Marlatt, Chairman. 

Insecticide and Fungicide Board J. K. Haywood, Chairman. 

Packers and Stockyards Administration John T. Caine, in Charge. 

Grain Futures Administration J. W. T. Duvel, in Charge. 



This bulletin is a contribution from 

Bureau of Plant Industry William A. Taylor, Chief. 

Office of Biophysical Investigations G. N. Collins, Senior Botanist in 

Charge. 

35 



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